The invention relates to a technique for controlling switching of a traveling mode of a hybrid electric vehicle.
Of recently-developed hybrid electric vehicles, some vehicles are known as being able to switch among an EV mode in which the vehicle travels by means of electric motors and through use of electric power fed from a drive battery without activating an engine, a series mode in which the vehicle travels by means of the electric motors while generating electric power by causing the engine to actuate a generator, and a parallel mode in which the vehicle travels by means of both the engine and the electric motors.
Patent Document 1 discloses a hybrid electric vehicle capable of switching among the EV mode, the series mode, and the parallel mode. Additionally disclosed is the technology of automatically selectively performing switching to the EV mode at a low vehicle speed and switching to the parallel mode at a high vehicle speed when a drive battery exhibits a high state of charge and switching to the series mode at the low vehicle speed and switching to the parallel mode at the high vehicle speed when the drive battery exhibits a low state of charge.    [Patent Document 1] JP-A-2011-156985